Double piston extender with torch on the side makes top one extend, but bottom piston flashes.

If you use the torch on the side of this vertical double piston extender, The top piston will extend first. While this happens, the head attached to the bottom piston will vanish/flash away for about 1 tick.
Pic: https://www.dropbox.com/s/9p9anhe06hv6vtd/2013-02-15_00.35.27.png